FRI257 Adrenal Insufficiency Secundary Due Immune Checkpoint Inhibitors Therapy

Disclosure: S.R. Rivera: None. J. Valencia: None. E. Figueroa: None. J. Calisto: None. Background: Immune checkpoint inhibitors (ICIs) are new anticancer immunotherapies that can trigger a variety of immune related adverse events (irAEs) in different organs, including the endocrine system. Adrenal insufficiency is uncommon with a nonspecific clinical presentation that must be recognized in time due to its potential mortality. Clinical Case: 41 year old man diagnosed with papillary renal cell carcinoma. He underwent surgery, performing a ​​right radical nephrectomy plus bilateral lymphadenectomy. He started chemotherapy in March 2022 with ICIs, Nivolumab and Ipilimumab. Three months later he presents with myalgias, fatigue and 6 kilogram weight loss. Physical exam: in regular conditions, vital signs with blood pressure 70/40 mmHg, heart rate 84 bpm, with no signs of hyperpigmentation or dehydration. No evidence of clinical hyperthyroidism. Lab results: low ACTH levels: 6.4 pg/ml (9 - 69 pg/ml), low cortisol: 0.06 µg/dl ( 6.02-18.4 µg/dl), low TSH: 0.1 µU/ml ( 0.4- 4.2 µU/ml) and normal free T4: 1.01 ng/dl ( 0.93-1.7 ng/dl). Antibody tests were negative: anti thyroglobulin, anti TPO and TRAB. Normal thyroglobulin levels. Sellar MRI was requested: normal, metastasis were ruled out. Thyroid ultrasound: normal thyroid gland. Exclusion of exogenous use of corticosteroids and levothyroxine was done. Case was interpreted as an adrenal insufficiency due to hypophysitis with associated thyrotoxicosis. Treatment with hydrocortisone was started, while thyroid function progression was observed. In the following lab control, elevation of TSH was noted. Two months later, we documented elevation of TSH levels: 5 µU/ml and decline of free T4 levels: 0.58 ng/dl, starting levothyroxine supplementation. Patient had a favorable clinical evolution. Conclusion: Adrenal insufficiency due to hypophysitis is uncommon and is mostly linked to Ipilimumab use. In those cases pituitary gland MRI is often normal most of the time. Thyroid involvement, which is frequently seen with Nivolumab therapy, varies from thyrotoxicosis, hyperthyroidism and hypothyroidism. Usually produces chronic damage and needs permanent treatment. The potentially lethal nature of these events makes it essential for oncologists and endocrinologists to be aware of these manifestations in order to achieve early treatment. Presentation: Friday, June 16, 2023